Calculator
An electronic calculator is a small, portable, often inexpensive electronic device used to perform both basic and complex operations of arithmetic. The first solid state electronic calculator was created in the 1960s, building on the extensive history of tools such as the abacus, developed around 2000 BC, and the mechanical calculator, developed in the 17th century. It was developed in parallel with the analog computers of the day. Pocket sized devices became available in the 1970s, especially after the invention of the microprocessor developed by Intel for the Japanese calculator company Busicom. Modern electronic calculators vary from cheap, give-away, credit-card sized models to sturdy desktop models with built-in printers. They became popular in the mid-1970s as integrated circuits made their size and cost small. By the end of that decade, calculator prices had reduced to a point where a basic calculator was affordable to most and they became common in schools. Computer operating systems as far back as early Unix have included interactive calculator programs such as dc and hoc, and calculator functions are included in almost all PDA-type devices (save a few dedicated address book and dictionary devices). In addition to general purpose calculators, there are those designed for specific markets; for example, there are scientific calculators which include trigonometric and statistical calculations. Some calculators even have the ability to do computer algebra. Graphing calculators can be used to graph functions defined on the real line, or higher dimensional Euclidean space. In 1986, calculators still represented an estimated 41% of the world's general-purpose hardware capacity to compute information. This diminished to less than 0.05% by 2007 Design Modern electronic calculators contain a keyboard with buttons for digits and arithmetical operations. Some even contain 00 and 000 buttons to make large numbers easier to enter. Most basic calculators assign only one digit or operation on each button. However, in more specific calculators, a button can perform multi-function working with key combination or current reckoning mode. Calculators usually have liquid crystal displays as output in place of historical vacuum fluorescent displays. See more details in technical improvements. Fractions such as 1&fras1;3 are displayed as decimal approximations, for example rounded to 0.33333333. Also, some fractions such as 1&fras1;7 which is 0.14285714285714 (to 14 significant figures) can be difficult to recognize in decimal form; as a result, many scientific calculators are able to work in vulgar fractions or mixed numbers. Calculators also have the ability to store numbers into memory. Basic types of these store only one number at a time. More specific types are able to store many numbers represented in variables. The variables can also be used for constructing formula. Some models have the ability to extend memory capacity to store more numbers; the extended address is referred to as an array index. Power sources of calculators are batteries, solar cells or electricity (for old models) turning on with a switch or button. Some models even have no turn-off button but they provide some way to put off, for example, leaving no operation for a moment, covering solar cell exposure, or closing their lid. Crank-powered calculators were also common in the early computer era. Category:Numbers